PSI - Issue 19

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 19 (2019) 140–149

Fatigue Design 2019 Fatigue analysis of cast iron components considering the influence of casting skin Kim Bergner a *, Jan Hesseler b , Christoph Bleicher b a System Reliability, Adaptive Structures and Machine Acoustics SAM, Technische Universität Darmstadt, Germany b Fraunhofer Institute for Structural Durability and System Reliability LBF, Darmstadt, Germany Abstract The assessment of the fatigue strength of castings with remaining casting skin still constitutes a challenge. Until now, only the roughness of the casting skin has been considered through a reduction factor during the design process. This reduction factor, however, neglects the influence of discontinuities such as inhomogeneous microstructures, imperfections, pores etc. In this work, the casting skin represents the rim zone of the casting, consisting of surface roughness and a deviating microstructure. To assess the influence of the casting skin on the fatigue strength, stress- and strain-controlled fatigue tests were conducted on EN GJS-400-15 specimens with deviating casting skins. The cyclic behavior of the rim zone microstructure was determined via cyclic axial strain-controlled tests under alternating loading R ε = -1 on small flat specimens removed from the rim zone. For the integration of the results from the axial fatigue tests with the influence of the surface roughness, as well as stress gradients present in cast components, on fatigue strength, cyclic bending tests under alternating R σ = -1 and pulsating loading R σ = 0 were performed. The test results are used to develop a fatigue approach to consider the influence of the rim zone on the fatigue life of cast iron components. Fatigue Design 2019 Fatigue analysis of cast iron components considering the influence of casting skin Kim Bergner a *, Jan Hesseler b , Christoph Bleicher b a System Reli bility, Adap ve Structu es and Machine Acoustic SAM, Technische Unive sität Darmstadt, Germany b Fraunhofer Institute for Structural Durability and System Reliability LBF, Darmstadt, Germany Abstract The asse sment of the fatigue strength of castings with rem ining asting skin still constitutes a chall nge. Until now, only the r ughn ss of the casting ski has been co s d red through a reduction facto du ing the design proce s. Thi reduction factor however, neglects th i fluence of discontinuitie such as inhomogeneous microstructures, imperfections, pores etc. In this work, the casting sk repres nts the rim zone of the castin , consisting of surface roughness and a deviating microstru ture. To assess the influence of e casting skin o the fatigue strength, stress- and stra n-c trolled fatigue t sts were conducted on EN GJS-400-15 specim ns with deviating casting skins. The cyclic behavior of the rim zone microstructure was d termin d via cyclic axial st ain-controlled tests under alternating loading R ε = -1 on small flat specimens removed from the rim zone. For th integration of the r sults from the axial fatigue tests with th influence of the surface roughness, s we l s stress gradi nts p esent in cast components, on fatigue strength, cyclic b nding tests under alt rnating R σ = -1 and pulsating loading R σ = 0 were p rf rmed. The test results are used to develop a fatigue approach to consider the influence of the rim zone on the fatigue life of cast iron components.

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. © 2019 The Autho s. Publ shed by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. Keywords: nodular cast iron, casting skin, fatigue strength, graphite degeneration Keywords: nodular cast iron, casting skin, fatigue strength, graphite degeneration

1. Introduction 1. Introduction

When it comes to component design, nowadays, the topic of lightweight design cannot be neglected. The goal is the reduction of resources and energy consumption as well as the reduction of CO 2 emissions. One step towards this When it comes t component design, nowadays, the topic of lightweight design cannot be neglected. The goal is the reduction of resources and energy consumption as well as the reduction of CO 2 emissions. One step towards this

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. * Correspon ing author. Tel.: +49 6151 705 8232; fax: +49 6151 705 214. E-mail address: bergner@sam.tu-darmstadt.de * Corresponding author. Tel.: +49 6151 705 8232; fax: +49 6151 705 214. E-mail address: bergner@sam.tu-darmstadt.de

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. 10.1016/j.prostr.2019.12.017